The present invention relates to a turbo-generator in which a vapor turbine part and a generator part are formed unitarily so that a casing therefor does not have any rotary shaft-passed part, whereby leakage of a turbine working fluid is prevented. This turbo-generator has a maintenance-free feature, and can be utilized not only in a gravitational field but also in space (gravity-free field).
In a conventional generating system using a vapor turbine, a vapor turbine part and a generator part are formed independently of each other and are separated definitely. A rotational force is transmitted mechanically between the turbine part and the generator part via their rotary shafts passed through their respective casings and connected together. Accordingly, slidable components, such as bearing and sealing mechanisms are provided in the vapor turbine part and the generator part, so that the generating system requires periodic maintenance. Therefore, the reliability of this generating system with respect to its continuous long-term use is low. Especially, the part of the generating system which is on the vapor turbine part side has a problem that vapor, a turbine working fluid, leaks to the outside through the bearings and sealing mechanisms, and this causes an absolute quantity of the working fluid in the system to decrease. In the case where the turbine working fluid consists of a radioactive fluid, the diffusion thereof has a very serious influence upon the environment.
A turbo-generator in which a vapor turbine part and a generator part are formed unitarily with a rotary body driven in a floated non-supported state has been proposed as a turbo-generator capable of solving these problems (refer to Japanese Patent Laid-Open No. 299439/1990). In this apparatus, a plurality of cup-shaped pressure-receiving buckets are provided at a circumferentially peripheral portion of a disc-like rotary body, and the rotary body is driven by the working fluid jetted against these buckets in a balanced state of the rotary body. Conductors or permanent magnets are fitted to the rotary body, and stationary permanent magnets or stationary conductors are so arranged as to face the conductors or permanent magnets fitted to the rotary body, whereby electric power is generated.
This prior art turbo-generator has succeeded in achieving the reduction of dimensions and weights thereof and obtaining a leakage-free and maintenance-free structure owing to the unification of the turbine and generator elements and to the no-bearing structure, and constitutes epochal techniques in these respects.
However, this prior art turbo-generator has many problems to be solved, which will be described below, before putting it to practical use. The turbine element has a cup-shaped pressure-receiving bucket structure, in which the rotating pressure-receiving buckets can be set only in a single stage, so that the turbine efficiency is low. In the generator element, a coil is wound only partially on a region in which electric power is generated, and a casing member is provided in a magnetic circuit. Therefore, it is difficult to raise the generating efficiency to a higher level. The stability of the rotary body is determined by only the interaction between the jetted vapor and cup-shaped pressure-receiving buckets, and so it is difficult to increase the stability. The temperature of the turbine working fluid is restricted by the acceptable temperature of the permanent magnets stably used in the generator part for a long period of time, which is currently around 200.degree. C. Thus, it is impossible at present to increase the working fluid temperature above the mentioned level.
Both the turbine element of a cup-shaped pressure-receiving bucket structure and the generator element of a partially coil wound structure provided with a casing-interposed part are wholly novel structures. In order to improve the generating efficiency it becomes necessary to newly develop the whole system because there is no experience in the designing and manufacturing such elements. Consequently, the time and money required for the development of the prior art turbo-generator described above necessarily becomes enormous.